A well-respected American neuroscientist warns that Republican presidential front-runner Donald Trump has a mental disorder that could make him a dangerous world leader.

Writing for Raw Story, neuroscientist and freelance science writer Bobby Azarian says Trump is a "textbook" narcissist "in the same category as a number of infamous dictators like Muammar Gaddafi, Napoleon Bonaparte, and Saddam Hussein."

At least two other mind experts—Harvard Professor and researcher Howard Gardener and clinical psychologist George Simon—share the same view. Simon even told Vanity Fair that "Trump is so classic that I'm archiving video clips of him to use in workshops."

According to the Mayo Clinic, narcissistic personality disorder is "a mental disorder in which people have an inflated sense of their own importance, a deep need for admiration and a lack of empathy for others."

Azarian says Trump exhibits all the characteristics of a narcissist.

First, Trump clearly demonstrates lack of empathy in the case of migrants, Azarian says. "Instead of recognising that the data shows that most Mexican immigrants are not violent, but instead people simply looking for a place where actual opportunity exists, with a broad brush [Trump] claims that they are 'criminals, drug dealers, rapists, etc.' In a similar vein, Trump has vowed to ban all Muslims from entering the country should he be elected," the mind expert says.

"It appears that his lack of empathy has distorted his mind's ability to grasp the fact that the refugees he speaks of are actually seeking safety from the same murderous maniacs that he wants to keep out," Azarian says.

A narcissist is someone who shows overwhelming arrogance and a delicate self-esteem that is easily hurt by any form of criticism, and Trump clearly demonstrates this, Azarian says. "We have all seen Trump unjustifiably lash out at a number of people with harsh and often extremely odd personal attacks. When he thought he had been treated unfairly by Fox News host and Republican debate moderator Megan Kelly, he responded by calling her a 'bimbo' and later saying that she had 'blood coming out of her eyes, blood coming out of her wherever,'" he points out.

To be fair, Azarian notes, not all narcissists are terrible people. Some of America's most beloved celebrities and musicians have been described as narcissists, including Elvis Presley, Marlon Brando, Kanye West, and even Alec Baldwin. "Not only are these decent people, some have also done a lot of good through philanthropic work," Azarian says.

However, all the celebrities mentioned confined themselves in the entertainment industry and did not aspire to become a political leader. Precisely because of his narcissistic personality, Trump found success in business and as a reality TV star, Azarian says.

But that is also the trait that makes him potentially dangerous as a political leader, he adds.

"What happens when another world leader who is a loose cannon doesn't give Trump the admiration that he feels he deserves? We can be sure that notoriously anti-American dictators like Kim Jong-un of North Korea or Iran's Supreme Leader Khamenei aren't going to give him any respect, let alone praise," Azarian says.

"How would a President Trump react when he feels he is being put down or undermined? Will we see the start of World War III because the leader of the most important nation in the world doesn't feel that others are kissing his ass as much as they should be?"

Azarian likens Trump to Gollum from "Lord of the Rings," with the U.S. presidency as his "one ring to rule them all."

But in this case, America does not have the option of destroying the ring. "The best we can strive for is keeping it out of the possession of those who cannot resist abusing its power," Azarian says.